1. Field of the Invention
The present invention relates to an apparatus for receiving image information for capturing images of an object by a plurality of imaging means to obtain image information. The invention also relates to a method of receiving image information for capturing images of an object by a plurality of imaging means to obtain image information.
2. Description of the Related Art
Considerable research and development has been carried out on three-dimensional image display techniques using a head-mounted display and a head-up display and so on for applications such as virtual reality and games.
In order to display a three-dimensional image of an object in general, image information obtained through acquiring images of the object from directions differing from one another is given to each of right and left eyes of a person. Therefore displaying a three-dimensional image of the object requires a plurality of imaging devices for capturing images of the object from directions differing from one another and a display for displaying a three-dimensional image of the object based on the image information obtained by the plurality of imaging devices.
For displaying a three-dimensional image of an object in motion, it is required that the plurality of imaging devices follow the object in motion. A conventional technique for providing a plurality of imaging devices following an object in motion is described in Shigeru Ando, `Real-time Three-dimensional Vision Sensing System`, in Interface, February 1995, pp. 94-104. The technique disclosed uses a binocular CCD camera (a pair of CCD cameras) mounted on an autonomously movable head-shaped base. An occurrence of an event in a field of view such as an occurrence of a movement is detected from outputs of the binocular CCD camera. The binocular CCD camera is then turned to a direction in which the event has occurred for determining which part is most important in the field of view. The CCD camera centers the part in the field of view. Consequently the CCD camera follows the object with its movement.
However, the technique described above requires an advanced adjustment mechanism between the two cameras for following an object in motion. Since the binocular CCD camera is fixed to the head-shaped base, it is required to maintain a symmetry between the two cameras with arbitrary movements of the field of view. A controller of the binocular CCD camera therefore incorporates a high-precision adjustment mechanism for video signal gains and binocular convergence angles, for example.
Three-dimensional image display techniques provide two systems in accordance with convergence angles of imaging devices and displays. The first of the two systems adopts two image acquisition devices located at a convergence angle of 0 degree (termed `parallel convergence` for the following description) and two displays located at a parallel convergence for displaying image information obtained by each of the imaging devices. The second of the two systems uses two imaging devices located at an arbitrary convergence angle and two displays located at an arbitrary convergence angle for displaying image information obtained by each of the imaging devices.
Three-dimensional image display for viewing requires techniques capable of creating a realistic effect with less fatigue of a viewer. In this respect, the two systems described above each have the following problems. The first system generates a parallax greater than that of human eyes between two images displayed since the imaging devices and the displays have no convergence. Consequently, viewer's fatigue is produced which is typical of three-dimensional image display. The second system produces viewer's fatigue typical of three-dimensional image display as well though less than that produced by the first system. When a viewer is viewing an object in a close range with a greater convergence angle, such a convergence angle is optically forced on both eyes of the viewer. Furthermore, a convergence angle is fixed for imaging devices and displays of many of present three-dimensional image display systems implemented through the second system. It is therefore impossible to follow arbitrary object position and viewer's position.